Question

I am a beginner in XSLT.

Below is source XML which i receive. Request tag constains the FlightId which is being used to filter the Result tag.

Source XML:

<Response>
    <Request>
        <RequestedFlights>
            <FlightId>2121</FlightId>
            <FlightId>2584</FlightId>
        </RequestedFlights>
    </Request>
    <Result>
        <Flights>
            <Flight>
                <Segments>
                    <Segment>
                        <Id>1</Id>
                        <FlightNumber>2121</FlightNumber>
                    </Segment>
                    <Segment>
                        <Id>2</Id>
                        <FlightNumber>1121</FlightNumber>
                    </Segment>
                </Segments>
            </Flight>
            <Flight>
                <Segments>
                    <Segment>
                        <Id>3</Id>
                        <FlightNumber>2121</FlightNumber>
                    </Segment>
                    <Segment>
                        <Id>4</Id>
                        <FlightNumber>2584</FlightNumber>
                    </Segment>
                </Segments>
            </Flight>
            <Flight>
                <Segments>
                    <Segment>
                        <Id>5</Id>
                        <FlightNumber>2121</FlightNumber>
                    </Segment>
                    <Segment>
                        <Id>6</Id>
                        <FlightNumber>2584</FlightNumber>
                    </Segment>
                    <Segment>
                        <Id>7</Id>
                        <FlightNumber>2023</FlightNumber>
                    </Segment>
                </Segments>
            </Flight>
        </Flights>
    </Result>
</Response>

XSLT:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="1.0">

    <xsl:output method="xml" indent="yes" />
    <xsl:variable name="ReqFlights" select="//Request/RequestedFlights/FlightId" />
    <xsl:variable name="FilterFlights" select="//Result/Flights/Flight[Segments/Segment/FlightNumber=$ReqFlights]"/>

    <xsl:template match="Response">
        <FilterResult>
            <ResultCount>
                <xsl:value-of select="count($FilterFlights)"/>
            </ResultCount>
            <xsl:copy>
                <xsl:copy-of select="$FilterFlights"/>
            </xsl:copy>
        </FilterResult>
    </xsl:template>
</xsl:stylesheet>

I received below output using above XSLT.

Output:

<FilterResult>
    <ResultCount>3</ResultCount>
    <Response>
        <Flight>
            <Segments>
                <Segment>
                    <Id>1</Id>
                    <FlightNumber>2121</FlightNumber>
                </Segment>
                <Segment>
                    <Id>2</Id>
                    <FlightNumber>1121</FlightNumber>
                </Segment>
            </Segments>
        </Flight>
            <Flight>
            <Segments>
                <Segment>
                    <Id>3</Id>
                    <FlightNumber>2121</FlightNumber>
                </Segment>
                <Segment>
                    <Id>4</Id>
                    <FlightNumber>2584</FlightNumber>
                </Segment>
            </Segments>
        </Flight>
            <Flight>
            <Segments>
                <Segment>
                    <Id>5</Id>
                    <FlightNumber>2121</FlightNumber>
                </Segment>
                <Segment>
                    <Id>6</Id>
                    <FlightNumber>2584</FlightNumber>
                </Segment>
                <Segment>
                    <Id>7</Id>
                    <FlightNumber>2023</FlightNumber>
                </Segment>
            </Segments>
        </Flight>
    </Response>
</FilterResult>

I would like to receive below output.

Expected Output:

<FilterResult>
    <ResultCount>1</ResultCount>
    <Response>
        <Flight>
            <Segments>
                <Segment>
                    <Id>3</Id>
                    <FlightNumber>2121</FlightNumber>
                </Segment>
                <Segment>
                    <Id>4</Id>
                    <FlightNumber>2584</FlightNumber>
                </Segment>
            </Segments>
        </Flight>
    </Response>
</FilterResult>

Please help me. How should i use the array to filter the response and get expected output.
Thanks.

Answer 1

Use:

/*/Result/*/Flight
            [count(*/*)=count(/*/Request/*/FlightId)
           and
             not(*/*/FlightNumber[not(. = /*/Request/*/FlightId)])
            ]

Here is the complete transformation:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:strip-space elements="*"/>

 <xsl:template match="/">
     <xsl:variable name="vHits" select=
     "/*/Result/*/Flight
                  [count(*/*)=count(/*/Request/*/FlightId)
                 and
                   not(*/*/FlightNumber[not(. = /*/Request/*/FlightId)])
                   ]"/>
    <FilterResult>
    <ResultCount><xsl:value-of select="count($vHits)"/></ResultCount>
    <Response>
     <xsl:copy-of select="$vHits"/>
    </Response>
  </FilterResult>
 </xsl:template>
</xsl:stylesheet>

When this transformation is applied on the provided XML document:

<Response>
    <Request>
        <RequestedFlights>
            <FlightId>2121</FlightId>
            <FlightId>2584</FlightId>
        </RequestedFlights>
    </Request>
    <Result>
        <Flights>
            <Flight>
                <Segments>
                    <Segment>
                        <Id>1</Id>
                        <FlightNumber>2121</FlightNumber>
                    </Segment>
                    <Segment>
                        <Id>2</Id>
                        <FlightNumber>1121</FlightNumber>
                    </Segment>
                </Segments>
            </Flight>
            <Flight>
                <Segments>
                    <Segment>
                        <Id>3</Id>
                        <FlightNumber>2121</FlightNumber>
                    </Segment>
                    <Segment>
                        <Id>4</Id>
                        <FlightNumber>2584</FlightNumber>
                    </Segment>
                </Segments>
            </Flight>
            <Flight>
                <Segments>
                    <Segment>
                        <Id>5</Id>
                        <FlightNumber>2121</FlightNumber>
                    </Segment>
                    <Segment>
                        <Id>6</Id>
                        <FlightNumber>2584</FlightNumber>
                    </Segment>
                    <Segment>
                        <Id>7</Id>
                        <FlightNumber>2023</FlightNumber>
                    </Segment>
                </Segments>
            </Flight>
        </Flights>
    </Result>
</Response>

the wanted, correct result is produced:

<FilterResult>
   <ResultCount>1</ResultCount>
   <Response>
      <Flight>
         <Segments>
            <Segment>
               <Id>3</Id>
               <FlightNumber>2121</FlightNumber>
            </Segment>
            <Segment>
               <Id>4</Id>
               <FlightNumber>2584</FlightNumber>
            </Segment>
         </Segments>
      </Flight>
   </Response>
</FilterResult>

Explanation:

Proper use of the double negation law.